Um, this is a very weird question... You took off the cat and did a straight pipe and put a fart cannon on it and you ask why its loud?

I hate to be harsh but why are you modifying cars if you can't figure this one out?

No cat means no expansion for the exhaust gases, and also the honey comb center will deaden the sound quite a bit, you removed that and put a ricer muffler on, which 90% of the time is a straight pipe glass packed muffler with a 2" inlet and a 4" coffee can outlet... so you now have almost no muffling system to your exhaust.